This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We have affinity purified MAZ from HeLa cells and analyzed the copurifying proteins by Maldi MS. The only protein identified was keratin. The experiment was repeated paying special care not to contaminate the sample with exogenous keratin. Again, the only protein identified was keratin. Keratin was only identified in the ~60 kDa gel lane (endogenous?). In addition, the control lane of a 1D SDS page gel did not differ significantly from the IP lane. The only visible difference was identified as MAZ. This could either be a degradation product or an alternative splicing product of full length MAZ. We continue to optimize the sample purification conditions.